Github user keith-turner commented on a diff in the pull request:
https://github.com/apache/accumulo/pull/256#discussion_r116300155
--- Diff:
core/src/main/java/org/apache/accumulo/core/file/blockfile/cache/BlockCacheManager.java
---
@@ -0,0 +1,121 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.accumulo.core.file.blockfile.cache;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.accumulo.core.conf.AccumuloConfiguration;
+import org.apache.accumulo.core.conf.Property;
+import org.apache.accumulo.start.classloader.vfs.AccumuloVFSClassLoader;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public abstract class BlockCacheManager {
+
+ public static final String CACHE_PROPERTY_BASE =
Property.GENERAL_ARBITRARY_PROP_PREFIX + "cache.block.";
+
+ private static final Logger LOG =
LoggerFactory.getLogger(BlockCacheManager.class);
+ private static BlockCacheManager manager = null;
+
+ protected final Map<CacheType,BlockCache> caches = new HashMap<>();
+
+ /**
+ * Initialize the caches for each CacheType based on the configuration
+ *
+ * @param conf
+ * accumulo configuration
+ */
+ public void start(AccumuloConfiguration conf) {
+ for (CacheType type : CacheType.values()) {
+ BlockCache cache = this.createCache(conf, type);
+ this.caches.put(type, cache);
+ }
+ }
+
+ /**
+ * Stop caches and release resources
+ */
+ public void stop() {
+ this.caches.clear();
+ close();
+ }
+
+ private static synchronized void close() {
+ manager = null;
+ }
+
+ /**
+ * Get the block cache of the given type
+ *
+ * @param type
+ * block cache type
+ * @return BlockCache or null if not enabled
+ */
+ public BlockCache getBlockCache(CacheType type) {
+ return caches.get(type);
+ }
+
+ /**
+ * Create a block cache using the supplied configuration
+ *
+ * @param conf
+ * cache configuration
+ * @return configured block cache
+ */
+ protected abstract BlockCache createCache(AccumuloConfiguration conf,
CacheType type);
+
+ /**
+ * Get the BlockCacheFactory specified by the property
'tserver.cache.factory.class' using the AccumuloVFSClassLoader
+ *
+ * @param conf
+ * accumulo configuration
+ * @return block cache manager instance
+ * @throws Exception
+ * error loading block cache manager implementation class
+ */
+ public static synchronized BlockCacheManager
getInstance(AccumuloConfiguration conf) throws Exception {
+ if (null == manager) {
+ String impl = conf.get(Property.TSERV_CACHE_FACTORY_IMPL);
+ Class<? extends BlockCacheManager> clazz =
AccumuloVFSClassLoader.loadClass(impl, BlockCacheManager.class);
+ manager = (BlockCacheManager) clazz.newInstance();
--- End diff --
I am still in favor of removing this static. I don't think its necessary.
I think if tserver wants to keep one instance, then it should keep a reference
to it. All the current static stuff we have is troublesome and we would like
to move away from it. Could rename this method to `newInstance` if you drop
the static.
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